After listening to this surprise release, I knew the song instantly. Did a bit of searching and here are some interesting facts. The song is sung by a group of rats called The Ratler Brothers as a parody of The Statler Brothers (no relation to the Muppets' constant heckler) who originally recorded the song in 1965.
If you know this song, then something didn't click when watching the video. That's because this being the Muppets they changed a few lines. "Watching instagrams and playing tons of sudaku", "catching up on all the things I've been meaning to do", and "mixing combustible chemicals the whole night through" are new lines; the original line is supposed to be "smoking cigarettes and watching Captain Kangaroo".
Fun video and this totally made my day feel better.